Further studies will be made of the mode of action of guinea pig lymphotoxin, especially with respect to its action on membrane transport systems. Work on the purification and characterization of rabbit lymphotoxin and rabbit lymph node cell mitogen will be continued in preparation for studies on the role of lymphokines in cellular immune injury in vivo. We are also initiating a study of the release of water-soluble marker from liposomes carrying Forssman hapten in their bilayer by lymph node cells in the presence of rabbit antibody to Forssman hapten. These experiments are aimed at determining whether the antibody-dependent lymphocyte mediated cytotoxicity is directed against the lipid bilayer of the plasma membrane. BIBLIOGRAPHIC REFERENCES: Gately, Maurice K., Mayer, Manfred M. and Henney, Christopher S. Effect of Anti-Lymphotoxin on Cell-Mediated Cytotoxicity. Evidence for Two Pathways, One Involving Lymphotoxin and the Other Requiring Intimate Contact Between the Plasma Membranes of Killer and Target Cells. Cellular Immunology, 27:82, 1976. Gately, Celia L. Gately, Maurice K. and Mayer, Manfred M. The Molecular Dimensions of Mitogenic Factor from Guinea Pig Lymph Node Cells J. Immunol., 114:10, 1975.